Investigations of the frequency of DNA strand breakage and cross-linking and of sister chromatid exchange in the lymphocytes of electric welders exposed to chromium- and nickel-containing fumes

Summary A total of 39 electric welders exposed to chromium and nickel were compared with 18 controls standardized for age, smoking habits and sex with respect to the frequency of sister chromatid exchange (SCE) and of DNA strand breakage and cross-linking (measured by the method of alkaline filter elution) in their blood lymphocytes. A significant correlation was found between the frequency of SCE and of individual DNA strand breakage and the concentration of chromium in the urine. Less DNA from the welders than from the control group was eluted through the two filter types used (polycarbonate and polyvinylidene fluoride filters). This must be interpreted as resulting from the presence of DNA-protein cross-links, which has the secondary effect of leading to a relative reduction in the measurable frequency of strand breakage amongst the welders. The present results are in good agreement with in vitro and in vivo investigations that confirm the importance of DNA-protein cross-links for the carcinogenic effect of chromium.     

Sister chromatid exchange frequency in workers exposed to high levels of ethylene oxide,in a hospital sterilization service

Summary Blood samples were taken from a group of 25 subjects professionally exposed to high levels of ethylene oxide (EO) during the past two years; the samples were compared to those from 22 control subjects, using sister chromatid exchange (SCE) methodology. The quantity of ethylene oxide inhaled during the two previous years was subsequently evaluated to fall between 500 and 5800 mg. When compared with the control group, the exposed group demonstrated a significant increase in the SCE rate. For certain individuals, the rate of increase rose 100% beyond the control mean. Smoking habits significantly influenced the data observed for the control group, but no significant differences in the SCE rate were found for the exposed group, regardless of smoking habits. Senior workers had the highest SCE mean levels. This observation indicated that the effect of exposure to EO was sufficient to produce a genetic reaction, was cumulative and in some cases persistent.     

染色单体互换频率与铅砷等危害的探讨

目的　探讨铅、镉、砷等职业有害因素致人外周血淋巴细胞染色体畸变的特征性改变。方法　采集职业作业人群及正常人群外周血淋巴细胞培养 72h ,观察染色体畸变类型及其特征。结果　因镉污染接触人群及实验室条件下对淋巴细胞进行高浓度染铅时染色单体互换畸变细胞率为 0 ;染砷浓度 <0 1mg/L时未发生染色单体互换 ,染砷浓度达 0 2～ 0 4mg/L时染色单体互换畸变细胞率为 1 2 4%。　结论　染色单体互换畸变细胞率的增加与接触因素砷及砷的浓度密切相关 ,砷是否可作为染色单体互换产生的主要原因还需作进一步深入的研究     

石油作业女性染色单体交换与习惯性流产关系研究

目的:分析石油作业女性外周血淋巴细胞姐妹染色单体互换(SCE)对习惯性流产的影响。方法:随机选择习惯性流产的石油作业女性26人为观察组和正常的育龄女性18人为对照组,检测其外周血淋巴细胞姐妹染色单体互换,记数SCE发生率。结果:观察组的外周血淋巴细胞SCE发生率为8.66±0.61明显高于对照组,差异有统计学意义(P<0.05)。结论:SCE的发生可作为石油作业习惯性流产女性染色体结构稳定性的检测指标。石油作业环境中的某些有害物质对女性DNA损伤有一定的影响。     

长期饮用不同浓度水氟人群外周血淋巴细胞SCE频率分析

报道了在正常营养与营养不足状态下,长期接触不同浓度水氟的人群外周血淋巴细胞姊妹染色单体交换(SCE)频率,以评价氟对人群的遗传毒性危险度。调查的人群组分为:0.2、1.0和4.8mg/L三个不同的饮水氟水平,每一组水氟浓度又分为正常营养与营养不足两组,共6个组。这些农民长期居住于该地区并饮用该氟浓度的水,年龄为40岁以上。结果表明,高浓度水氟未引起人群SCE频率增加,即本研究未发现氟的遗传毒性作用。     

Sister chromatid exchange induction by the herbicide 2,4-dichlorophenoxyacetic acid in chick embryos

As genetic damage may result from exposure to agricultural chemicals, it seemed appropriate to assess the genotoxic potential of 2,4-dichlorophenoxyacetic acid (2,4-D), a widely used broad-leaf herbicide, using a test system that may provide some indications on the genetic risk to animal species in the wild. In the present study, sister chromatid exchange (SCE) induction and cell cycle kinetics alterations by 2,4-D in 4-day old chick embryos were evaluated. Both a commercial herbicide formulation containing 37% 2,4-D isooctyl ester as active ingredient and pure 2,4-D were tested. Chick embryos were treated with 0, 0.5, 1, 2, or 4 mg 2,4-D. Test solutions were applied to the inner shell membrane on day 0 of incubation. Either commercial formulation or pure 2,4-D induced a dose-related increase in SCE frequency over the concentration range from 0 to 4 mg/embryo. Significantly higher SCE frequency was seen for the 4-mg group of embryos treated with the commercial product. A slightly higher SCE value was observed for the vehicle group (acetone-treated embryos) compared with the negative controls (untreated embryos). Significant inhibition of cell cycle progression was evident in both experimental groups and was generally dose related. The extent of changes in cell kinetics was similar in both groups, although somewhat more marked in the group treated with pure 2,4-D. The present findings corroborate the positive results from recent in vivo rodent studies.     

Effect of sulfur dioxide hydrates on cell cycle, sister chromatid exchange, and micronuclei in barley

The effects of sulfur dioxide (SO(2)) hydrates exposure on cell cycle, sister chromatid exchange (SCE), and micronuclei (MN) were investigated in barley (Hordeum vulgare) roots. A mixture of sodium bisulfite and sodium sulfite (1:3), at various concentrations from 1x10(-5) to 3x10(-2)M, was used for the treatments. The results showed that the mixture induced the formation of SCE and MN in barley root cells with different effective concentrations and with different trends as treatment concentrations increased. At high concentrations of 0.5-30.0mM, SO(2) hydrates inhibited the mitotic activity and the growth of barley roots by cell cycle delay and cell death, but at 0.1mM, the chemicals slightly stimulated mitotic activity and root growth. These remarkable effects in causing DNA damage and consequent chromosome damage suggest that SO(2) is genotoxic agent and its genotoxicity may influence the mitotic activity and plant growth under SO(2) stress.     

Long-term monitoring of sister chromatid exchanges and micronucleus frequencies in pharmacy personnel occupationally exposed to cytostatic drugs

Objectives: Many antineoplastic drugs were found to have carcinogenic, mutagenic and teratogenic potential. The aim of this study was to carry out cytogenetic and internal dose monitoring of hospital pharmacy personnel regularly involved in the preparation of cytostatic agents, in order to test possible cytostatics-induced genotoxic effects due to occupational exposure under routine working conditions, and in cases of accidental contamination. Methods: Platinum in whole blood and anthracyclines in plasma were measured to assess internal exposure to cytostatics. The level of cytogenetic damage was determined in peripheral blood lymphocytes with the micronucleus test and the sister chromatid exchange assay. Five series of monitoring were performed over a period of 2 years. Results: No significant differences in the mean frequencies of sister chromatid exchanges (SCE) and micronuclei (MN) were found between occupationally exposed probands and controls (9.9 ± 1.4 vs 10.1 ± 1.2 SCEs/cell and 21.2 ± 7.2 vs 23.3 ± 7.5 MN/2000 binucleated (BN) cells, n=16). Significant elevations of SCE or MN were detected in seven out of 12 cases of accidental contamination at the workplace, whereas no increase in platinum in blood and anthracyclines in plasma was observed in these probands. Two cases of non-reported contamination were identified by measurement of epirubicin in plasma. Smoking was found to increase the SCE significantly. No correlation between individual SCE scores and MN scores was observed. Conclusions: Our findings support a transient increase in SCE or MN after relevant exposure to cytostatic drugs in cases of accidental contamination. The lack of significant differences in SCE and MN between hospital pharmacy personnel and unexposed controls, points to high standards of safety at the corresponding workplaces. Received: 11 October 1999 / Accepted: 25 April 2000     

Ambient and biochemical effect monitoring of workers exposed to ethylene oxide

Objectives: Ethylene oxide is an alkylating agent known to be a directly acting mutagen and carcinogen. This study describes the relationship between workplace ambient air concentrations of ethylene oxide and the concentration of N-2-hydroxyethylvaline in the globin of exposed workers. Methods: During the sterilization of medical equipment, 12 workers were occupationally exposed to ethylene oxide. Personal and stationary ambient air measurements were carried out to monitor the external exposure. The determination of the protein adducts was based on the N-alkyl-Edman method, introducing a new commercially available dipeptide standard for calibration purposes. Results: Ethylene oxide concentrations ranging from 0.2 to 8.5 ppm were found in the workplace air. The adduct concentrations ranged from 5,219 to 32,738 pmol N-2-hydroxyethylvaline/g globin in the case of regularly exposed workers (n = 9) and from 518 to 3,321 pmol N-2-hydroxyethylvaline/g globin for three persons with occasional contact with ethylene oxide. Conclusions: The Deutsche Forschungsgemeinschaft established in 1993 a relationship between the ethylene oxide concentration in ambient air and the amount of N-2-hydroxyethylvaline in human globin. By extrapolation, constant exposure to 1 ppm ethylene oxide should yield approximately 4,000 pmol N-2-hydroxyethylvaline/g globin. The ambient air concentrations of ethylene oxide and the amount of N-2-hydroxyethylvaline determined within the present study confirm this extrapolation in practice. In addition, the determination of adducts based on the use of commercially available dipeptide standards for calibration purposes turned out to be an advantageous alternative to the commonly used protein standards. Received: 18 February 1997 / Accepted: 9 June 1997     

Biological monitoring of hospital pharmacy personnel occupationally exposed to cytostatic drugs: urinary excretion and cytogenetics studies

For evaluation of the risk borne by hospital pharmacy personnel exposed to antineoplastic agents, the incorporation of cyclophosphamide, ifosfamide, and platinum-containing drugs was quantified by the determination of urinary concentrations. In addition, the induction of micronuclei (MN) and sister-chromatid-exchange (SCE) rates in peripheral blood lymphocytes were studied for correlation with the urinary excretion of cytostatic drugs. Cyclophosphamide and ifosfamide were determined in 24-h urine samples using gas chromatography with electron capture (detection limit 2.5 μg/l). Voltammetric analysis enabled the determination of platinum concentrations of 4 ng/l. Heparinized blood (20 ml) was drawn and lymphocytes were cultured for MN and SCE studies. In all, 13 hospital pharmacists and pharmacy technicians regularly involved in the preparation of cytostatic drugs participated in this investigation (7 persons represent a follow-up group). All subjects applied standard safety precautions, including the use of a vertical laminar air-flow hood, protective gowns, and latex gloves. On the day of urine sampling an average of 4,870 mg cyclophosphamide, 5,580 mg ifosfamide, and 504 mg platinum-containing drugs were handled. The excretion of 5 and 9 μg cyclophosphamide/1 urine was measured in two samples, respectively. An elevated level of urinary platinum was found in one pharmacist (22.3 ng/g creatinine) in comparison with a nonexposed control group. Mean frequencies of MN and SCE did not differ significantly between the drug exposed group and control group. The employees who had incorporated chemotherapeutic agents were part of the follow-up group and, thus, particularly cautious and sensitive to a possible hazard. The results emphasize the necessity of improving personal protection of hospital pharmacy personnel occupationally exposed to cytostatic drugs and support the importance of biological monitoring. In an ongoing project in our department the sources of contamination are being investigated parallel to biological monitoring so as to determine critical situations and improve personal protection. Received: 7 August 1996 / Accepted: 3 January 1997     

Biological monitoring of methylhexahydrophthalic anhydride by determination of methylhexahydrophthalic acid in urine and plasma from exposed workers

Objective: To investigate whether methylhexahydrophthalic acid (MHHP acid) in urine and plasma can be used as a biomarker for exposure to methylhexahydrophthalic anhydride (MHHPA). Methods: MHHPA in air was sampled by Amberlite XAD-2 and analysed by gas chromatography (GC) with flame ionisation detection. MHHP acid in urine and plasma was analysed by GC with mass spectrometric detection. Workers occupationally exposed to MHHPA were studied. Air levels of MHHPA were determined by personal sampling in the breathing zone. Urinary levels of MHHP acid, a metabolite of MHHPA, were determined in 27 workers. In eight workers all urine was collected at intervals during 24 h. Plasma levels of MHHP acid were determined in 20 workers. Results: The time-weighted average (TWA) air levels ranged from 5 to 60 μg MHHPA/m³ during 8-h work-shifts. The urinary levels of MHHP acid increased during exposure and decayed after the end of exposure with an estimated half-life of about 6 h. A correlation was found between the TWA air levels of MHHPA and creatinine-adjusted MHHP acid levels in urine collected during the last 4 h of exposure. A correlation was also seen between the TWA air levels of MHHPA and the plasma concentrations of MHHP acid. An exposure to 20 μg MHHPA/m³ corresponded to about 140 nmol MHHP acid/mmol creatinine and about 40 nmol MHHP acid/l plasma. Conclusion: The results indicate that MHHP acid in urine or plasma may be used for biological monitoring of the exposure to MHHPA. Received: 4 October 1996 / Accepted: 2 January 1997     

Correlation between urinary methoxyacetic acid and exposure of ethylene glycol dimethyl ether in a lithium battery plant

Objective To examine the correlation between airborne ethylene glycol dimethyl ether (EGdiME) exposures and the urinary methoxyacetic acid (MAA) and to approach the issue of a permissible exposure limit for EGdiME. Methods The survey was conducted on Thursday. Workers occupationally exposed to EGdiME, as well as nonexposed controls, were studied in combination with one of the authors, who was coincidentally exposed to EGdiME while carrying out the study. Air levels of EGdiME were determined by personal sampling on passive gas tubes. Urine was collected from nine control subjects and ten workers immediately before and after the shift, and from one of the authors at intervals during 12 h. The analyses of EGdiME in air and MAA in urine were performed by gas chromatography with flame ionization detection. Results The time-weighted average (TWA) air levels of EGdiME ranged from 0.7 to 10.5 ppm during 8 h work shifts. The urinary levels of MAA in one of the authors increased continuously during exposure and after the end of exposure. The levels of urinary MAA in the exposed workers were significantly higher than those in the control subjects. On the other hand, the postshift values were higher than the preshift values in the exposed workers, but the difference was not significant. A linear correlation was found between the TWA air levels of EGdiME and creatinine-adjusted MAA levels in urine collected at the end of the shift (r = 0.933; P < 0.0001). According to our equation, a linear extrapolation to the biological limit value recommended by Shih et al. (1999) of 40 mg MAA/g crea indicated an average inhalation exposure to EGdiME over the workweek of 12 ppm. Conclusions These results indicate that the determination of MAA in urine is suitable for use in the biological monitoring of EGdiME exposure.     

DNA single strand breakage, DNA adducts, and sister chromatid exchange in lymphocytes and phenanthrene and pyrene metabolites in urine of coke oven workers.

OBJECTIVES: To investigate the specificity of biological monitoring variables (excretion of phenanthrene and pyrene metabolites in urine) and the usefulness of some biomarkers of effect (alkaline filter elution, 32P postlabelling assay, measurement of sister chromatid exchange) in workers exposed to polycyclic aromatic hydrocarbons (PAHs). METHODS: 29 coke oven workers and a standardised control group were investigated for frequencies of DNA single strand breakage, DNA protein cross links (alkaline filter elution assay), sister chromatid exchange, and DNA adducts (32P postlabelling assay) in lymphocytes. Phenanthrene and pyrene metabolites were measured in 24 hour urine samples. 19 different PAHs (including benzo(a)pyrene, pyrene, and phenanthrene) were measured at the workplace by personal air monitoring. The GSTT1 activity in erythrocytes and lymphocyte subpopulations in blood was also measured. RESULTS: Concentrations of phenanthrene, pyrene, and benzo(a)pyrene in air correlated well with the concentration of total PAHs in air; they could be used for comparisons of different workplaces if the emission compositions were known. The measurement of phenanthrene metabolites in urine proved to be a better biological monitoring variable than the measurement of 1-hydroxypyrene. Significantly more DNA strand breaks in lymphocytes of coke oven workers were found (alkaline filter elution assay); the DNA adduct rate was not significantly increased in workers, but correlated with exposure to PAHs in a semiquantitative manner. The number of sister chromatid exchanges was lower in coke oven workers but this was not significant; thus counting sister chromatid exchanges was not a good variable for biomonitoring of coke oven workers. Also, indications for immunotoxic influences (changes in lymphocyte subpopulations) were found. CONCLUSIONS: The measurement of phenanthrene metabolites in urine seems to be a better biological monitoring variable for exposure to PAHs than measurement of hydroxypyrene. The alkaline filter elution assay proved to be the most sensitive biomarker for genotoxic damage, whereas the postlabelling assay was the only one with some specificity for DNA alterations caused by known compounds.     

Formic acid excretion in comparison with methanol excretion in urine of workers occupationally exposed to methanol

Summary A semiautomated head-space gas chromatographic (GC) method was developed for measuring formic acid in urine. The method consists of heating 1 ml urine sample in a 20-ml air-tight vial in the presence of 1 ml sulfuric acid and 2 ml ethanol at 60°C for 30 min for ethyl esterification and air-liquid equilibrium, followed by automatic injection of 1 ml head-space air into a flame ionization detector GC. The detection limit was 1 mg/l for formic acid. The method was applied to measure formic acid in the shift-end urine samples from 88 workers exposed to methanol at 66.6 ppm (as geometric mean) and in urine samples from 149 nonexposed controls. Methanol concentrations were also determined. Regression analysis showed that urinary formic acid concentrations, as observed or corrected for either creatinine concentration or specific gravity of urine (1.016), correlated significantly with time-weighted average intensities of exposure to methanol vapor. Men excreted significantly more formic acid than women. Comparison with methanol excretion suggested, however, that urinary formic acid is less sensitive than urinary methanol as an indicator of methanol vapor exposure, primarily because the background level for formic acid (26 mg/l as arithmetic mean, or 23 mg/l as geometric mean) is more than ten times higher than the level for methanol (1.9 mg/l as arithmetic mean, or 1.7mg/l as geometric mean). After theoretical methanol exposure at infinite concentration, the urinary formic acid/methanol ratio should be about 0.4.     

Gaschromatographic determination of butoxyacetic acid after hydrolysis of conjugated metabolites in urine from workers exposed to 2-butoxyethanol

For the gaschromatographic determination of total butoxyacetic acid (BAA), i.e., free plus conjugated BAA in urine, we studied the acid hydrolysis condition to cleave the conjugate. The optimum condition for hydrolysis was chosen to be 60 min boiling of the mixture of 1 ml twofold diluted urine and 1.2 ml hydrochloric acid. For the biological monitoring of workers exposed to 2-butoxyethanol (BE), we applied our acid hydrolysis method to the urine from 6 workers exposed to the solvent for 7 days and determined total BAA as well as free BAA and conjugated BAA, which was calculated as the difference between the concentrations of free and conjugated BAA. The percentages of conjugated BAA vs. total BAA varied from 44.4% to 92.2% (mean value 71.1 %) among 6 individual workers over 7 days and decreased gradually over the consecutive work days. In the latter half of the work week, free BAA comparatively accounted for the larger portion of urinary BAA. Significant correlations were found between urinary BAA concentrations and BE levels in the breathing-zone air (TWA). The correlation coefficients of urinary concentrations of total or conjugated BAA vs. BE levels was higher than that of free BAA concentrations vs. BE levels. Hence, the determination of total BAA in urine is a suitable test for the biological monitoring of BE exposure, because of the simplicity in procedures and the good agreement with BE exposure levels.     

Biological monitoring of workers occupationally exposed to carbon disulphide in a rayon plant in Brazil: Validity of 2-thiothiazolidine-4-carboxylic acid (TTCA) in urine samples taken in different times, during and after the real exposure period

Fifteen workers from a rayon plant in Brazil were monitored. Air samples were taken during a mean period of 5.8 hours out of an 8 hour workshift, in three different adsorbing tubes. Five urine samples were taken at 4 hour interval from the beginning of the shift, and at the beginning of the next shift in which 2-thiothiazolidine-4-carboxylic acid (TTCA) concentration was analysed. Data from seventeen individuals were statistically studied, with the aim of establishing the best and the most practical sampling strategy of biological monitoring for workers occupationally exposed to CS₂. For those chronically exposed to CS₂, TWA air concentration lower than 30 and higher than 10 mg/m³, it was found that the higher the exposure levels, the lower was TTCA concentration in the end of shift urine samples. The results may be explained by dietary habits and/or by the small number of examined population or even eventual casualty. On the other hand they raise other hypothesis involving the chronicity of exposure which may lead to important changes in metabolism influencing the excretion rate of TTCA.     

Concentrations of benzene in blood and S-phenylmercapturic and t,t-muconic acid in urine in car mechanics

Summary Different parameters of biological monitoring were applied to 26 benzene-exposed car mechanics. Twenty car mechanics worked in a work environment with probably high benzene exposures (exposed workers); six car mechanics primarily involved in work organization were classified as non-exposed. The maximum air benzene concentration at the work places of exposed mechanics was 13 mg/m³ (mean 2.6 mg/m³). Elevated benzene exposure was associated with job tasks involving work on fuel injections, petrol tanks, cylinder blocks, gasoline pipes, fuel filters, fuel pumps and valves. The mean blood benzene level in the exposed workers was 3.3 g/l (range 0.7–13.6 g/1). Phenol proved to be an inadequate monitoring parameter within the exposure ranges investigated. The muconic and S-phenylmercapturic acid concentrations in urine showed a marked increase during the work shift. Both also showed significant correlations with benzene concentrations in air or in blood. The best correlations between the benzene air level and the mercapturic and muconic acid concentrations in urine were found at the end of the work shift (phenylmercapturic acid concentration: r = 0.81, P < 0.0001; muconic acid concentration: r = 0.54, P < 0.05). In conclusion, the concentrations of benzene in blood and mercapturic and muconic acid in urine proved to be good parameters for monitoring benzene exposure at the workplace even at benzene air levels below the current exposure limits. Today working as a car mechanic seems to be one of the occupations typically associated with benzene exposure.